Existing methods for monitoring the distribution of biological entities in vivo require covalent or genetic modification of the entity. Such modification may result in the behaviour of the biological entity in vivo being modified.
Therapeutic applications where viruses are administered to a subject are in development. These applications include gene therapy and tumour destruction (oncolytic virotherapy) (Lui et al (2007)). In the development of these therapies it is a requirement to be able to monitor the distribution of the virion following administration without altering its infectivity (Herschman (2003); Yamamoto and Curiel (2010))
Monitoring the distribution of virions following administration is problematic employing existing methods. Tissue biopsy is invasive and is of limited use in clinical trials (Kuruppu and Tanabe (2005); Waehler et al (2007)). Non-invasive methods such as magnetic resonance imaging (MRI), positron emission tomography (PET) and X-ray computed tomography (CT) usually require image enhancing agents or chemical modification of the virion (Piwnica-Worms et al (2004); Strable and Finn (2009)).
Viruses may be engineered to incorporate reporter genes. However, monitoring the expression of these genes only indicates where the genes of the virus are being expressed (Peng et al (2003); Waehler et al (2007)).
It is an object of this invention to provide a convenient alternative to these existing methods with application to biological entities in addition to enveloped viruses (virions).